This cool shot shows Marine Corps MV-22 Osprey generating Kopp-Etchell’s effect in the dust

Nov 23 2015 - 2 Comments

A U.S. Marine Corps Osprey tilt-rotor aircraft is depicted with seemingly solid rotor disks.

The image in this post shows a U.S. Marine Corps MV-22 Osprey assigned to Special Purpose MAGTF – CR – CC during a TRAP (tactical recovery of aircraft and personnel) drill at an undisclosed location in Southwest Asia, on Nov. 16, 2015.

What makes the shot particularly interesting (and vaguely Star Wars-like…) is the halo effect caused by the sand hitting the blades and eroding their metal surface. The effect is more visible around the blades’ tips where the peripheral speed is higher.

Caused by the oxidation of eroded particles, the so-called “Kopp-Etchells effect” (named by war correspondent Michael Yon after Cpl. Benjamin Kopp, and Cpl. Joseph Etchells, two fallen American and British soldiers) makes the tilt-rotor aircraft more visible from distance, hence more vulnerable.

Image credit: U.S. Marine Corps. H/T @DCDude1776 for the heads-up

  • William Dix

    It’s not just tilt rotors that get affected by the Kopp-Etchells effect it’s a problem for many different types of rotor craft. In fact it affects any rotor crafts blade leading edge being abraded by dust particles. The metals used in the abrasion strips that shield the leading edges of rotor blades from abrasion (and propeller blades for the matter) are often Pyrophoric. There are photos showing the same effects in CH-47 Chinooks, CH-53s and UH-60 Blackhawks.

    There’s a good explanation here of the phenomenon.

  • Tesla_X

    Consider a few probable combined effects:

    Heat caused by friction, electrostatics or ionization, and that intensely heated silicon dioxide is flammable at certain high temperatures.

    Some have even proposed harnessing the effect to provide power using turbines and purify silicon for manufacturing simultaneously.

    The glass powder coating that results from combusting silicon compounds though is not easy to jackhammer off engine parts.

    Or it could just be as simple as something like flint on a rock, but with different materials and happening many thousands of times a second with really tiny impacts.

    Interesting effect to see though…looks cool!